Add I/O extender support to Venus

[dirkjanfaber]

This issue is about adding support for the I/O extender (and other switching devices).

When plugged in the GX, the device adds digital inputs as we are used to, (under com.victronenergy.digital_input etc) because it is an USB device. The device does contain an eeprom, so we know the serial (see dmesg output below).

More complex devices end up under com.victronenergy.switch.iox_$serial, and perhaps some of the configuration of the io extender will be placed there too. E.g. the state of the dipswitches.

Affected repositories (needs to be checked, possibly not altered):

• systemcalc ibu / rvz
• node-red-contrib-victron dfa
• venus-platform rvz
• gui jho
• gui-v2 rvz
• dbus_modbus_tcp dfa
• vecan-dbus mbo
• dbus-generator (running state, digital input) rvz
• VRM - For switching the relays (and digital io?) dfa
• HTML5 app mma

[511157.709507] usb 6-1: new full-speed USB device number 3 using ohci-platform
[511157.992646] usb 6-1: New USB device found, idVendor=10c4, idProduct=ea90, bcdDevice= 0.00
[511158.001143] usb 6-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[511158.008408] usb 6-1: Product: GX IO-Extender 150
[511158.013229] usb 6-1: Manufacturer: Victron Energy BV
[511158.018430] usb 6-1: SerialNumber: HQ24200AFFE
[511158.032731] cp2112 0003:10C4:EA90.0002: hidraw0: USB HID v1.01 Device [Victron Energy BV GX IO-Extender 150] on usb-1c1d400.usb-1/input0
[511158.120561] cp2112 0003:10C4:EA90.0002: Part Number: 0x0C Device Version: 0x03

[ReinvdZee]

On Venus OS 3.60~17, the IO extender is recognized properly. The inputs will be picked up by dbus-digitalinputs. The GUI used to show the digital inputs by deriving the input number from the path com.victronenergy.settings/Settings/DigitalInput/<n>/ to show it as "Digital Input ". This only accepted integers. I changed the GUI to show the input label instead: com.victronenergy.digitalinputs/Devices/x/Label, like the GUI does for analog inputs.

Now, the digital inputs are automatically picked up and shown as:

[ReinvdZee]

I added PWM support for the IO extender. To support hotplugging the PCA9632 chip (PWM driver in the io extender), I patched the driver such that it uses a default configuration when there are no device-tree nodes found. Which will be the case, since it is loaded with udev which can't pass any devicetree nodes.

I also modified the udev rules and the ioextender script such that the pwm channels show up in /var/run/io-ext/<SN>/pwm<x>. Write 0-255 to /pwm<x> to control the duty-cycle of the PWM output.